A large undeveloped oil field in a national rainforest reserve in Ecuador will remain off-limits to oil companies for at least a year, the government said. Ecuadorean President Rafael Correa agreed to keep oil companies out of the Yasuni National Park in the Amazon. The pledge was part of a $110 million fund drive to convince the government to keep the reserve untapped potentially through 2013, the Platts news service reports. The Ishpingo-Tambococha-Tiputini field, in the Yasuni National Park that is part of the Amazon rainforest, holds an estimated 1 billion barrels of heavy crude oil, Platts notes. State-owned energy company Petroecuador in mid-December said it was spending millions of dollars to clean Amazon sites polluted by oil. Some of those sites are tied to Chevron\'s work in the region. Plaintiffs in Ecuador blame Texaco, which Chevron bought in 2001, for environmental contamination and adverse health effects tied to operations in the country\'s rainforests from 1972-90. Authorities in Ecuador denied claims that Chevron donated some of the money to the rainforest measure to appease the government.